1. Field of the Invention
The present invention relates to an apparatus and method for Automatic White Balance (AWB) with supplementary sensors. More particularly, the present invention relates to an apparatus and method for providing the AWB using supplementary sensors, or more than one sensor.
2. Description of the Related Art
The use of image capture devices, which may include still image cameras, moving image cameras or other electronic devices that include cameras, has rapidly increased in recent years along with advancements in camera technology. For example, digital cameras are now commonly included in mobile communication terminals, such as cell phones, smart phones, portable computers, tablet computers, and other similar electronic devices. Additionally, advancements in camera technology have provided a proliferation of less expensive and higher quality cameras available to consumers and camera users. For example, an amount of pixels per photographic still image has increased, and other advancements have been made to improve an image quality of the photographs captured by cameras.
Digital cameras allow for a group of settings to be selected or adjusted by a user selecting a scene type description or an image capture mode, such as outdoors, indoors, sunny, close-up, candlelight, nighttime, and other similar scene type descriptions. Among the group of settings, Automatic White Balance (AWB) is used to determine and/or adjust color temperatures and to determine a temperature of neutral colors, such as a color white. By determining and adjusting the color temperature of white, color temperatures of the remaining colors are also adjusted in order to adjust a color composition of a captured image.
In order to perform an AWB, a variety of algorithms and methods may be used by cameras, such as illumination estimation, a Bayesian method, Retinex models, Von Kries' method, a grey world assumption method or other similar algorithms and methods. An AWB operation estimates or determines color temperatures according to assumptions and data or statistics corresponding to sensor data. For example, the gray world assumption method assumes that the color in each sensor channel averages to gray over the entire image, and adjusts the color of white according to the assumption.
Cameras, as noted above, may have a variety of capture modes. When the user chooses a camera mode that is appropriate for the environmental conditions in which an image is to be captured, cameras produce a higher quality image resulting in better pictures because of additional information provided the capture mode selected by the user. The capture modes noted above may include capture modes that provide a scene or environmental condition information for the AWB operation. The scene or environmental condition information may be included in such capture modes sunny, cloudy, incandescent, and fluorescent, or other similar capture modes describing lighting or environmental conditions.
The capture modes are used to narrow a range of the possible color temperatures of light sources in the image to be captured. However, when a camera is set to an AUTO mode that precludes a user from selecting a capture mode, the camera may have to determine the scene or environmental condition information according to the statistics of the captured images by using an AWB algorithm or method.
Some AWB algorithms try to collect better statistics by collecting statistics only from pre-determined or effective regions, that is, the areas that might better satisfy the assumptions upon which the AWB algorithms operate. However, for certain images to be captured, using statistics only from the effective regions does not create photographs having proper colors. In other words, AWB behaves relatively well in most cases but fails to produce color correct images in certain situations, such as when a large bulk of water or a uniform surface is present in the image to be captured. Accordingly, there is a need for an apparatus and method for providing improved AWB.